Consolidate standalone wporg GitHub repos into the Meta repo

[obenland]

Several WordPress.org projects live in standalone GitHub repos (e.g. ​wporg-theme-directory, ​wporg-two-factor) with their own build workflow. This makes for a quite disparate contributor experience and it's not always clear where to make changes when debugging things on Dotorg.

Proposal

Move the self-contained repos into the meta repository, following the pattern already established by ​wporg-plugins-2024, which commits its @wordpress/scripts build output directly:

• Migrate code into its docroot location, e.g. wporg-themes-2024 → wordpress.org/public_html/wp-content/themes/pub/wporg-themes-2024. (wporg-theme-directory already mirrors this layout under source/wp-content/.)
• Commit build/ output in the repo, so patches/PRs are directly deployable via the wordpress.org GitHub sync script.
• Port each repo's lint/test workflows into path-filtered CI on the meta repo.
• Add a build-freshness check per project: CI runs npm ci && npm run build and fails on git diff --exit-code -- build/, to make sure that committed build files always match their source.
• Retire the per-repo build.yml and i18n.yml workflows — translate.wordpress.org picks up meta SVN directly.

Out of scope

wporg-mu-plugins and wporg-parent-2021 should probably stay put for now: their build branches are mounted by wp-env configs across many repos (including meta's own environments/). They can be moved in a later step.